Handheld mobile wireless palm-type communication devices such as Personal Digital Assistant (PDA) display terminals, e.g. PalmPilots™ and, of course, the wide variety of mobile wireless telephones, e.g. cellular telephones, have undergone a great expansion in usage in recent years and have been building a user base of hundreds of millions of these devices in present usage throughout the world. The small size and easy portability of these handheld devices makes them subject to often continual movement and rough handling, e.g. in briefcases, luggage, automobile glove boxes, shirt and other personal clothing pockets. All of these handheld devices have data entry keys ranging from a small number of control buttons to full alphanumeric keypads. The rough handling of these devices continuously exposes their input keys/buttons to inadvertent or random striking. The undesirable results of such striking may vary from the inadvertent telephone call or open line in cellular phones to corruption of data in PDAs, and, of course, attendant battery drainage. The current technology has developed many schemes for protecting input keys from such inadvertent or stray strikes. There have been electromechanical keypad covers that add a cumbersome aspect to the device and is likely to wear down with continuous usage. Other current solutions involve user initiated implementation wherein buttons/keypads may be disabled during transit. This has the troublesome result of having the user reactivate the keys when the device is turned on for usage and requires extra operations to be performed before the device is fully functional.
It should also be noted that users of handheld palm-type devices may frequently be technically unsophisticated. Thus, there is a need for keypad protection implementations that are simple, intuitive and user friendly. The present invention, which will be hereinafter described, provides such a simple implementation involving the user's hand itself. The invention is distinguishable from the existing technology of fingerprint identification as a means of locking or unlocking one specific user's computers through the sensing of a combination of physical characteristics, particular to only one user.